| Nowadays countries in the world face the energy crisis and environmental deterioration, and developing electric vehicle industry has become one of the important ways of energy conservation and emission reduction. These years for its simple structure, no emission, higher efficiency of energy using, electric vehicle has been favored by various governments and big companies all around the world. The industrial development of power battery and its application technology is the key to the electric vehicle industrial development, which is also the bottleneck of the development. Battery Management System is the core of the power battery application technology. BMS is necessary to the safety, optimizing use and executing the finished vehicle power management strategy for ensuring the good performance of battery pack and extending the life of battery pack. Effective management and control of BMS can ensure the safety and cost of the battery, and influence the promotion of electric vehicle. BMS research has great theoretical value and practical significance.This topic designs a BMS according to the general design requirements. The process includes: consulting massive literature; Overall project design; Modular design; Hardware design; Software design; Debugging, test data, analysis, conclusion and the suggestion at last. The BMS designed in this paper adopts the distributed structure with the main and auxiliary controllers, which can complete collecting basic data including battery voltage, temperature of battery box and working current, balancing battery pack, testing insulation resistance, estimating SOC, analysising fault and alarm, controlling relay, communicating with CAN, displaying with PC and portable, etc.Hardware system adopted16bit MCU from freescale as the master control chip and PIC12F675from microchip company as the auxiliary chip, AD7280A chips from ADI as the main monitoring chip to design various function circuits. Based on CodeWarrior and MPLAB software development environment, software system designs controlling strategy of main and sub program belongs to main and auxiliary controller with C.In addition, the system adopts the design of electromagnetic interference resistance, and CRC check were used to ensure the system can work stable in complex environment, and keep high accuracy in communication network.Correlation method is adopted to the system test, the results show that the work of BMS is stable, which can realize the management and control effectively; System can collect the data of current, voltage and temperature accurately, estimate SOC accurately, use high power SMD resistors to balance of the battery pack, transfer the network data stability and accurately.Main innovation points of the Paper are:using the test circuit of daisy chain with several AD7280As, which can test different kinds of Li-ion battery pack with simplifing the circuit and reducing the isolators; BMS tests the value of insulation resistance by means of column resistance pressure equation, for the safety of the vehicle, combines with ampere-hour integral and the open circuit voltage method for estimating SOC, and introducts the capacity attenuation parameter of the charging and discharging cycle, to improve the accuracy for estimating SOC. |
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